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[/] [or1k/] [trunk/] [newlib-1.10.0/] [newlib/] [libm/] [mathfp/] [sf_tan.c] - Blame information for rev 1767

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/* @(#)z_tanf.c 1.0 98/08/13 */
/******************************************************************
 * The following routines are coded directly from the algorithms
 * and coefficients given in "Software Manual for the Elementary
 * Functions" by William J. Cody, Jr. and William Waite, Prentice
 * Hall, 1980.
 ******************************************************************/
/******************************************************************
 * Tangent
 *
 * Input:
 *   x - floating point value
 *
 * Output:
 *   tangent of x
 *
 * Description:
 *   This routine calculates the tangent of x.
 *
 *****************************************************************/
 
#include "fdlibm.h"
#include "zmath.h"
 
static const float TWO_OVER_PI = 0.6366197723;
static const float p[] = { -0.958017723e-1 };
static const float q[] = { -0.429135777,
                            0.971685835e-2 };
 
float
_DEFUN (tanf, (float),
        float x)
{
  float y, f, g, XN, xnum, xden, res;
  int N;
 
  /* Check for special values. */
  switch (numtestf (x))
    {
      case NAN:
        errno = EDOM;
        return (x);
      case INF:
        errno = EDOM;
        return (z_notanum_f.f);
    }
 
  y = fabsf (x);
 
  /* Check for values that are out of our range. */
  if (y > 105414357.0)
    {
      errno = ERANGE;
      return (y);
    }
 
  if (x < 0.0)
    N = (int) (x * TWO_OVER_PI - 0.5);
  else
    N = (int) (x * TWO_OVER_PI + 0.5);
 
  XN = (float) N;
 
  f = x - N * __PI_OVER_TWO;
 
  /* Check for values that are too small. */
  if (-z_rooteps_f < f && f < z_rooteps_f)
    {
      xnum = f;
      xden = 1.0;
    }
 
  /* Calculate the polynomial. */
  else
    {
      g = f * f;
 
      xnum = f * (p[0] * g) + f;
      xden = (q[1] * g + q[0]) * g + 1.0;
    }
 
  /* Check for odd or even values. */
  if (N & 1)
    {
      xnum = -xnum;
      res = xden / xnum;
    }
  else
    {
      res = xnum / xden;
    }
 
  return (res);
}
 
#ifdef _DOUBLE_IS_32BITS
 
double tan (double x)
{
  return (double) tanf ((float) x);
}
 
#endif /* _DOUBLE_IS_32BITS */

Line No.	Rev	Author	Line
1	1010	ivang
2			`/* @(#)z_tanf.c 1.0 98/08/13 */`
3			`/******************************************************************`
4			`* The following routines are coded directly from the algorithms`
5			`* and coefficients given in "Software Manual for the Elementary`
6			`* Functions" by William J. Cody, Jr. and William Waite, Prentice`
7			`* Hall, 1980.`
8			`******************************************************************/`
9			`/******************************************************************`
10			`* Tangent`
11			`*`
12			`* Input:`
13			`* x - floating point value`
14			`*`
15			`* Output:`
16			`* tangent of x`
17			`*`
18			`* Description:`
19			`* This routine calculates the tangent of x.`
20			`*`
21			`*****************************************************************/`
22
23			`#include "fdlibm.h"`
24			`#include "zmath.h"`
25
26			`static const float TWO_OVER_PI = 0.6366197723;`
27			`static const float p[] = { -0.958017723e-1 };`
28			`static const float q[] = { -0.429135777,`
29			`0.971685835e-2 };`
30
31			`float`
32			`_DEFUN (tanf, (float),`
33			`float x)`
34			`{`
35			`float y, f, g, XN, xnum, xden, res;`
36			`int N;`
37
38			`/* Check for special values. */`
39			`switch (numtestf (x))`
40			`{`
41			`case NAN:`
42			`errno = EDOM;`
43			`return (x);`
44			`case INF:`
45			`errno = EDOM;`
46			`return (z_notanum_f.f);`
47			`}`
48
49			`y = fabsf (x);`
50
51			`/* Check for values that are out of our range. */`
52			`if (y > 105414357.0)`
53			`{`
54			`errno = ERANGE;`
55			`return (y);`
56			`}`
57
58			`if (x < 0.0)`
59			`N = (int) (x * TWO_OVER_PI - 0.5);`
60			`else`
61			`N = (int) (x * TWO_OVER_PI + 0.5);`
62
63			`XN = (float) N;`
64
65			`f = x - N * __PI_OVER_TWO;`
66
67			`/* Check for values that are too small. */`
68			`if (-z_rooteps_f < f && f < z_rooteps_f)`
69			`{`
70			`xnum = f;`
71			`xden = 1.0;`
72			`}`
73
74			`/* Calculate the polynomial. */`
75			`else`
76			`{`
77			`g = f * f;`
78
79			`xnum = f * (p[0] * g) + f;`
80			`xden = (q[1] * g + q[0]) * g + 1.0;`
81			`}`
82
83			`/* Check for odd or even values. */`
84			`if (N & 1)`
85			`{`
86			`xnum = -xnum;`
87			`res = xden / xnum;`
88			`}`
89			`else`
90			`{`
91			`res = xnum / xden;`
92			`}`
93
94			`return (res);`
95			`}`
96
97			`#ifdef _DOUBLE_IS_32BITS`
98
99			`double tan (double x)`
100			`{`
101			`return (double) tanf ((float) x);`
102			`}`
103
104			`#endif /* _DOUBLE_IS_32BITS */`

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[/] [or1k/] [trunk/] [newlib-1.10.0/] [newlib/] [libm/] [mathfp/] [sf_tan.c] - Blame information for rev 1767